Dual image slide and/or video projector

ABSTRACT

A dual image displaying apparatus ( 10 ) is disclosed including a first light source ( 12 ) for emitting light through a first image ( 14 ) onto a surface and a second light source ( 20 ) for emitting light through a second image ( 22 ) onto the same or another surface. The first image may be produced by a slide whilst the second image is produced by a display receiving and converting electrical image information into the second image. Typically, this is a liquid crystal display (LCD). The apparatus further includes a plurality of filters and other optical components ( 16, 24, 30, 32 ) to assist in producing a good quality image as well as protecting the LCD. Instead of a slide, the first image may also be produced by an LCD.

The present invention relates to an image projector with two or moreimage projecting capabilities. In particular the present invention maybe used to simultaneously display static and a moving image and whereinthe moving image may be provided by the use of a liquid crystal displaypanel (LCD).

BACKGROUND OF THE INVENTION

Slide and movie projectors are well known and have been used for anumber of years. In their simplest form they include of a light sourcethat projects an image to a screen. There are numerous types ofprojectors such as slide projectors that are adapted to transmit lightthrough a photographic slide. Lately, there have been proposed imageprojectors that use a fixed LCD to project a moving image. These devicesdo not, however, allow the use of conventional slides, being dedicatedto the use of LCD's to display an image.

The technological advances of LCD's, and especially the total number ofpixels being in the hundreds of thousands, have meant that theresolution of images using LCD's is of a very high quality. Hence it isdesirable to use LCD projectors not only in the business but also thepersonal environment. However, there are a still a large number ofimages only available on conventional slides and a dedicated LCDprojector apparatus would not be able to display those images.Consequently it may be necessary to have a number of differentprojecting apparatus including video image projectors and slideprojectors.

Furthermore, there is at times a requirement to project several imagessimultaneously. For example, one may project two images of differentdata or two scenes. Once again, one of the images may be that from aslide whilst the other may be produced by the use of an LCD. There iscurrently no apparatus known to the applicant of being able to producetwo different images, at least one of which may be an image from aconventional slide.

It is therefore an object of the present invention to overcome at leastsome of the abovementioned problems or to provide the public with auseful alternative by providing for an image display apparatus adaptedto project at least two images, wherein at least one of the images isproduced by the use of a LCD, whilst the other may be produced eitherfrom another LCD panel or a conventional slide.

BRIEF SUMMARY OF THE INVENTION

Therefore, in one form of the invention, though this need not be theonly or indeed the broadest form there is provided an image displayingapparatus including:

a first light source for emitting light though a first image onto asurface;

a second light source for emitting light through a second image onto thesame or another surface;

wherein said second image is produced by a display receiving andconverting electrical image information into the second image.

In preference said display is a liquid crystal display panel.

Preferably said first image is a conventional photographic slide.

Preferably the first image is produced by a display receiving andconverting electrical image information into the first image.

Advantageously disposed between said second image and said second lightsource is at least one filter.

Advantageously said filter is at least a ultra-violet or infraredfilter.

In preference disposed between the second image and the second lightsource is a heat filter.

In a further form of the invention there is proposed an image projectingapparatus adapted for the projection of at least two images including:

a first light source adapted to project light through a first image,through at least one optical component, focussing lens and onto asurface;

a second light source adapted to project light through a second image,through at least one other optical component, focussing lens and onto asecond surface, said second image being produced by a liquid crystaldisplay screen;

a plurality of filters disposed between said light sources and saidimages.

Advantageously the focussing lenses are adapted to be angularlyadjustable the two images are adapted to be superimposed on each other.

In preference said apparatus further includes a video or compact discmedia player.

Preferably the image projecting apparatus further includes a televisionscreen to display the image to be played through the image display.

Other objects and advantages of the present invention will becomeapparent in view of the following detailed description and accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate several implementations of theinvention and, together with the description, serve to explain theadvantages and principles of the invention. In the drawings,

FIG. 1 illustrates a top cross-sectional view of a typical dual imageprojector according to the present invention; and

FIG. 2 illustrates a general perspective view of a dual image projector.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following detailed description of the invention refers to theaccompanying drawings. Although the description includes exemplaryembodiments, other embodiments are possible, and changes may be made tothe embodiments described without departing from the spirit and scope ofthe invention. Wherever possible, the same reference numbers will beused throughout the drawings and the following description to refer tothe same and like parts.

With reference to the above figures there is shown a dual imageprojection apparatus 10 including a first light source 12 for emittinglight through a first image display device 14, said light then opticallymodified by optical components 16 and passing through a second imagedisplay device 22, said light then optically modified by second opticalcomponents 24 and passing through a second focussing lens 26 to bedisplayed on a screen.

The light sources 12 and 20 are lamps of the type generally found inslide projectors. The optical components 16 and 24 may include variousfilters such as infrared filters, ultra-violet filters and polarisers.

The first image display device can either be a conventional photographicslide or a LCD adapted to be used as a conventional slide. Consequently,the apparatus further includes a slide holder 28 which can supportmultiple slides and which in operation can be controlled to feeddifferent slides into the apparatus.

The second image display slide is a fixed LCD panel that also includesappropriate filters to protect the LCD from the parts of the spectrum ofthe second light source. Typically, said filters will include aultra-violet, infrared and pre-polariser filter 30 as well as polariser32. The LCD may also further include heat shields that can either beintegral with the filters or are separately positioned between thesecond light source and the LCD panel.

As disclosed by the applicant in co-pending application entitled“IMPROVEMENTS IN LCD'S ADAPTED FOR IMAGE PROJECTION USING A SLIDEPROJECTOR OR OTHER LIGHT SOURCE” which is intended to be incorporated byreference herein, using a conventional LCD in a typical slide projectorwill cause irreversible damage to the LCD under the influence ofdamaging ultraviolet and infrared radiation. The use of heat shieldsalone will not completely eliminate the damage to the LCD because ultraviolet rays degrade the LCD and the epoxy plug that holds the liquidcrystal in place, causing leakage and degradation which could lead tothe destruction of the LCD panel in time.

That co-pending application overcomes the problems of using aconventional LCD in a projector. Up to three filters are provided beinga polarising filter, an ultraviolet filter, and a heat/infra red filter.For convenience the filters may be mounted integrally on the LCD panelalthough it is to be understood that this is a preferred not anessential feature.

The polarising filter is mounted on the LCD side facing the lamp withinthe slide projector. Disposed on top of the polarising filter is theultra-violet filet. The heat/infra red filter must be located as far asis practicable form the LCD. In manufacture, the three filters may besequentially placed on the LCD. Alternatively, they may be adhered toeach other to provide for a laminated construction and then mounted onthe LCD. The mounting may be achieved using suitable mechanical bracketsor fasteners such as retaining clips.

Furthermore, in a preferred embodiment there is a preferred order in theplacement of filters.

Of course, it is important that the filters that block heat or otherpotentially damaging parts of the spectrum be located as far from thepanel as practicable to ensure no damage to the LCD. It is alsonecessary to use polarisers on the other side of the LCD. That dependsvery much on the particular structure of the LCD which can be bought asan off-the shelf product. It is also to be understood that thepolarisation must be linear so that the image that is projected is ofthe highest quality definition.

The use of thin filters advantageously allows the LCD device to beconstructed of a size able to be inserted into a conventional slideprojector enabling an image to be formed whilst protecting the LCD. Thefilters do not need to be mounted integrally on the LCD but may form aseparate laminate construction that is locked into place adjacent theLCD in a housing made up of two shells that engage the LCD panel and thelaminate filter construction. The construction housing may haveventilation holes/slots to allow circulation of air between the LCDpanel and the filters thus further protecting the LCD.

The shells may be correspondingly shaped and designed that one isslightly smaller than the other and frictionally engage each other.Alternatively, the housings may have appropriate lugs and recesses andmay be joined together in a snap-lock type of arrangement.

Thus, the present invention also uses those particular filters and inthat order to ensure that the LCD is protected. These filters may alsobe removable wherein on of the images is a conventional slide and thevarious filters are not required.

The apparatus includes a power supply 34 providing electrical power tothe two light sources and electronic circuit boards 36 that assist inproviding an image to the LCD panel 22. The whole apparatus may becontrolled via remote control, receiver 38 adapted to receive remoteinformation from a transmitter (not shown).

The focussing lenses 18 and 26 enable an image of different sizes to bedisplayed on a screen or other surface area. Obviously, the greater thedistance between the focusing lenses and the screen, the larger theimage.

According to the invention, each lens 18, 26 includes conventionaladjustment means for changing the focal length between the opticalcomponents 16, 24 and the lenses 18, 26. As will be appreciated by onehaving ordinary skill in the art, the adjustment means can comprisevarious mechanical arrangements.

In a preferred embodiment, each lens body 15, 25 includes a threaded end17 a, 17 b having a plurality of threads 17 disposed thereon. The lenscaps 19, 27 include internal threads that are adapted to cooperate withthe lens body threads 17, wherein when the caps 19, 27 are rotated onthe lens bodies 15, 25 the focal length between the lens caps 19, 27and, hence, optical lenses disposed therein, and the optical components16, 24 changes, whereby the focus of the images on the screen changes.

The focusing lenses 18 and 26 are further preferably adapted to beangularly adjustable, whereby the two images projected by the lenses 18,26 can be superimposed on each other. By the term “angularlyadjustable”, as used herein, it is means to mean that the lenses 18, 26are adapted to rotate on substantially coincident planes forming anglesα and α′ with respect to their longitudinal axes, designated A and A′,respectively (See FIG. 1).

The apparatus 10 may include other additional features such as a videotape player 40 adapted to play vide tapes 42 and further including aviewing screen 44 allowing the tape to be viewed either before and/orduring the image being projected through lens 26. The apparatus may alsoinclude input connectors 46 allowing an external electrical signal to befed to it.

Thus the present invention is for an apparatus that is not only capableof projecting video images but has the additional advantage of being aslide projector as well. The LCD panel can be activated independently ofthe slide display. In fact the slide display can itself include a LCDpanel so that there may be two video images displayed by the apparatus.The slide mechanism may be a conventional one, either top or sideloading.

It is also understood that additional features may be added to thepresent apparatus including but not limited to the following:

over-temperature cut-out to protect the slide and/or LCD

amplifier with external speakers and a microphone jack

disc drive for CD-ROM's or DVD's for showing prepared presentations

zoom/focussing optical componentry

television tuner card

image manipulation capabilities such as mirroring and reversing to usein rear projection.

audio output for connection to external sound systems

battery power

on screen display

remote I/R laser pointer

video sender in remote control

video sender T/R—wireless

Other improvements to the apparatus may be the ability to change theangle of the projection of one image compared to the other.Consequently, it may be possible to superimpose the images onto eachother.

Further advantages and improvements may very well be made to the presentinvention without deviating from its scope. Although the invention hasbeen shown and described in what is conceived to be the most practicaland preferred embodiment, it is recognized that departures may be madetherefrom within the scope and spirit of the invention, which is not tobe limited to the details disclosed herein but is to be accorded thefull scope of the claims so as to embrace any and all equivalent devicesand apparatus.

What is claimed is:
 1. An image displaying apparatus, comprising: afirst light source for emitting first light, said first light beingtransmitted substantially linearly though a first image onto a firstsurface, said first image being produced by a first display receivingand converting first electrical image information into said first image;and a second light source for emitting second light, said second lightbeing transmitted substantially linearly through a second image ontosaid first surface, said second image being produced by said firstdisplay receiving and converting second electrical image informationinto said second image.
 2. The image displaying apparatus of claim 1,wherein said display comprises a liquid crystal display panel.
 3. Theimage displaying apparatus of claim 1, wherein said first imagecomprises a conventional photographic slide.
 4. An image projectingapparatus adapted for the projection of at least two images, comprising:a first light source adapted to project first light substantiallylinearly through a first image and at least one first optical componentto a first focussing lens; a second light source adapted to projectsecond light substantially linearly through a second image and at leasta second optical component to a second focussing lens, said second imagebeing produced by a liquid crystal display screen, said first and secondlenses being angularly adjustable, whereby said first and second imagescan be superimposed on each other; and a plurality of filters disposedbetween said first and second light sources and said first and secondimages.
 5. The image displaying apparatus of claim 4, wherein saidplurality of filters include a ultra-violet filter, an infrared filterand a pre-polariser filter.
 6. The image displaying apparatus of claim4, wherein said apparatus includes at least one heat shield.
 7. Theimage displaying apparatus of claim 6, wherein said heat shield isdisposed between said second light source and said display screen.
 8. Amethod of displaying an image on a display screen, comprising the stepsof: providing an image displaying device having a first light source,said first light source being adapted to emit first light; transmittingsaid first light through a first image display device; opticallymodifying said first light with at least a first optical component toprovide first optically modified first light; transmitting said firstoptically modified first light through a second image display device;optically modifying said first optically modified first light with atleast a second optical component to provide second optically modifiedfirst light; and transmitting said second optically modified first lightthrough a focussing lens onto the display screen.